This invention relates to an electrical musical instrument that produces musical tone signals in accordance with manually selected note information and manually or automatically selected function information that is encoded in binary form and stored in a memory via time division multiplexing techniques.
Electrical musical instruments, such as electronic organs, have included circuits which transfer note selection information from keyboard switches to suitable memories by using time division multiplexing techniques. Examples of such circuits respectively employing pulse position encoding and binary encoding are shown in U.S. Pat. No. 3,610,799 of Watson and U.S. Pat. No. 3,844,379 of Tomisawa et al. As discussed in the introductory portion of the Watson patent, an important advantage of multiplexing arises from the resulting substantial reduction in the amount of electrical wiring needed to transfer the information from the keyboard to the tone selection portion of the organ.
A multiplexing system also can be utilized to transfer information other than note selection information. For example, a separate multiplexing system is described in column 20 of the Watson patent for transferring information from tab switches to control voicing circuitry. This system reduces the amount of wiring relative to that which would be required if the multiplexing system were not utilized. However, this reduction is only achieved at the expense and complication of an additional multiplexing system separate and apart from the note selection system. Furthermore the memories employed by the organ in the Watson patent store the selected note codes only as long as the corresponding note keys are held down by the organist.
Many electronic organs are provided with special effect circuits which, when enabled, automatically produce special musical effects such as arpeggio or strum, by sequentially gating to an output the tone signals selected by means of the keyboard switches. Unfortunately, due to the transient nature of storage of the note codes in such prior circuits, the organist must hold down the keys of the notes corresponding to the tone signals to be utilized by the special effects circuit in order for the function to be performed. The organist is thus precluded from performing other musical functions with one of his hands, to the same extent as if the selected musical functions were manually performed.